The plots of the estimated Rt over the last week show a steady decrease in Rt, resulting in a value very close to 1.0 in England. The greater mobility induced by the return to school is currently showing no signs of increasing transmission to problematic levels. The incidence of deaths has been gradually increasing since mid-June, although the actual numbers remain low in comparison to the peaks of the first two waves of infection. Similar to our most recent publication, our projections for the number of deaths suggest that we may have reached a peak.
Plots of the IFR over time show that from the end of January we estimate a decreasing IFR in all adult age groups, but most steeply in the older ages. This drop indicates the benefits of immunisation against death over and above the benefits against infection. Following this drop, over the last month there has been a slight increase to 3.6% (3.4%–4.0%) in the over-75s and 0.25% (0.23%–0.27%) overall.
For context, in addition to the data used here, the numbers of reported new positive tests (by date of specimen) are currently showing a downward trend approaching 20,000 per day, suggesting around 50% of infections are being identified. These case numbers are, however, highly dependent on the volume and targeting of testing, the public’s testing behaviour and might be subject to significant reporting delay, and therefore are difficult to interpret. Levels of hospital admission are beginning to decline in some regions, while the prevalence of infection, as estimated by the ONS Coronavirus Infections Survey, has fallen slightly below 1.3% in England.
Real-time tracking of an epidemic, as data accumulate over time, is an essential component of a public health response to a new outbreak. A team of statistical modellers at the MRC Biostatistics Unit (BSU), University of Cambridge, are working to provide regular now-casts and forecasts of COVID-19 infections and deaths. This information feeds directly to the SAGE sub-group, Scientific Pandemic Influenza sub-group on Modelling (SPI-M), and to regional Public Health England (PHE) teams.
We fit a transmission model (Birrell et al. 2020) to a number of data sources (see ‘Data Sources’), to reconstruct the number of new COVID-19 infections over time in different age groups and NHS regions, estimate a measure of ongoing transmission and predict the number of new COVID-19 deaths.
We use:
Data are stratified into eight age groups: <1, 1-4, 5-14, 15-24, 25-44, 45-64, 65-74, 75+, and the NHS England regions (North East and Yorkshire, North West, Midlands, East of England, London, South East, South West).
Value of \(R_t\), the average number of secondary infections due to a typical infection today.
The percentage of a given group that has been infected.
NB: negative growth rates are rates of decline. Values are daily changes.
| Region | Median | 95% CrI (lower) | 95% CrI (upper) |
|---|---|---|---|
| England | 0.00 | -0.01 | 0.01 |
| East of England | -0.02 | -0.04 | 0.01 |
| East Midlands | 0.01 | -0.02 | 0.03 |
| London | -0.02 | -0.05 | 0.00 |
| North East | 0.00 | -0.02 | 0.02 |
| North West | 0.00 | -0.03 | 0.03 |
| South East | 0.01 | -0.02 | 0.03 |
| South West | -0.05 | -0.08 | -0.03 |
| West Midlands | -0.01 | -0.04 | 0.02 |
| Yorkshire and The Humber | -0.01 | -0.03 | 0.02 |
Halving times in days, if a region shows growth than value will be NA.
| Region | Median | 95% CrI (lower) | 95% CrI (upper) |
|---|---|---|---|
| England | 1155.08 | 65.92 | NA |
| East of England | 43.77 | 15.31 | NA |
| East Midlands | NA | 41.43 | NA |
| London | 34.02 | 15.05 | NA |
| North East | NA | 29.16 | NA |
| North West | NA | 24.69 | NA |
| South East | NA | 43.94 | NA |
| South West | 13.08 | 8.40 | 25.4 |
| West Midlands | 61.60 | 19.10 | NA |
| Yorkshire and The Humber | 125.57 | 20.64 | NA |
Doubling times in days, if a region shows decline then the value will be NA.
| Region | Median | 95% CrI (lower) | 95% CrI (upper) |
|---|---|---|---|
| England | NA | 76.54 | NA |
| East of England | NA | 86.01 | NA |
| East Midlands | 92.55 | 23.58 | NA |
| London | NA | 218.36 | NA |
| North East | 247.91 | 28.09 | NA |
| North West | 377.42 | 23.84 | NA |
| South East | 78.59 | 23.49 | NA |
| South West | NA | NA | NA |
| West Midlands | NA | 44.95 | NA |
| Yorkshire and The Humber | NA | 35.00 | NA |
NB: negative growth rates are rates of decline. Values are daily changes.
| Region | Median | 95% CrI (lower) | 95% CrI (upper) |
|---|---|---|---|
| England | -0.01 | -0.01 | 0.00 |
| East of England | -0.02 | -0.03 | 0.00 |
| East Midlands | 0.00 | -0.02 | 0.02 |
| London | -0.01 | -0.02 | 0.01 |
| North East | 0.00 | -0.02 | 0.02 |
| North West | 0.00 | -0.02 | 0.02 |
| South East | 0.00 | -0.01 | 0.02 |
| South West | -0.02 | -0.03 | -0.01 |
| West Midlands | -0.01 | -0.03 | 0.00 |
| Yorkshire and The Humber | -0.01 | -0.02 | 0.01 |
Halving times in days, if a region shows growth than value will be NA.
| Region | Median | 95% CrI (lower) | 95% CrI (upper) |
|---|---|---|---|
| England | 114.08 | 56.85 | 4087.27 |
| East of England | 35.66 | 20.40 | 337.31 |
| East Midlands | NA | 43.28 | NA |
| London | 84.29 | 28.41 | NA |
| North East | 186.56 | 32.36 | NA |
| North West | NA | 41.84 | NA |
| South East | NA | 47.41 | NA |
| South West | 35.02 | 21.76 | 119.94 |
| West Midlands | 48.68 | 24.39 | NA |
| Yorkshire and The Humber | 79.45 | 28.80 | NA |
Doubling times in days, if a region shows decline then the value will be NA.
| Region | Median | 95% CrI (lower) | 95% CrI (upper) |
|---|---|---|---|
| England | NA | NA | NA |
| East of England | NA | NA | NA |
| East Midlands | 2223.49 | 36.52 | NA |
| London | NA | 76.34 | NA |
| North East | NA | 45.32 | NA |
| North West | 435.29 | 30.08 | NA |
| South East | 1189.63 | 39.58 | NA |
| South West | NA | NA | NA |
| West Midlands | NA | 190.23 | NA |
| Yorkshire and The Humber | NA | 88.20 | NA |
## The execution of the prevalence code block will proceed if
## prev.dat exists and this is TRUE
## it is not and external report and this is FALSEThe shaded areas show periods of national lockdown, the green lines the dates (once confirmed) of the steps in the roadmap in the UK Governement’s COVID-19 Response – Spring 2021, and the red line shows the date these results were produced (17 Sep).
The figure below shows the probability that \(R_t\) is greater than 1 (ie: the number of infections is growing) in each region over time. Clicking the regions in the legend allows lines to be added or removed from the figure.
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